Seal device and method for operating the same and substrate processing apparatus comprising a vacuum chamber

ABSTRACT

The present invention provides a seal device comprising a sealing passage which allows communication between a first space and a second space, and evacuation lines individually connected to the first space and the sealing passage. A gas feed line for feeding dry gas is connected to the sealing passage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/404,065, filed on Apr. 2, 2003, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a seal device for providing a sealbetween two spaces having different pressures, and to a method foroperating the same, and also relates to a substrate processing apparatuscomprising a vacuum chamber. More specifically, the present inventionrelates to a non-contacting seal device capable of providing a suitableseal in a semiconductor manufacturing apparatus between two spaceshaving different pressures and method for operating the same, and alsorelates to a substrate processing apparatus comprising a vacuum chamberin which a stage device is provided, wherein a substrate for producing asemiconductor or a liquid crystal is loaded on the stage device andprocessed in the vacuum chamber. In the substrate processing apparatusof the present invention, the vacuum chamber is appropriately controlledso that a good vacuum environment produced in the vacuum chamber can bemaintained.

Conventional non-contacting seal devices for providing a seal betweenspaces having different pressures are disclosed in U.S. Pat. Nos.4,118,042, 4,191,385 and 4,425,508. The seal devices disclosed in theabove documents are used in a clean environment, such as a vacuumenvironment, in which a movement (a rotary motion or a linear motion) ofan object is effected. The purpose of using these seal devices is toeffect a high-speed or smooth movement of the object without any risk ofcontamination of the clean environment.

Non-contacting seal devices tend to be used in the following two cases:when an object to be moved and a minimal structure are provided in aclean environment and a drive source and a guide mechanism for movingthe object are provided outside the clean environment; and when anon-contact type bearing such as a static fluid bearing (e.g., an airbearing) is provided and a clean environment is sealed without reducingthe merit of the non-contact type bearing. In the latter, (1) the staticfluid bearing is provided within a clean environment, and the cleanenvironment is sealed against fluid of the static fluid bearing, or (2)the bearing is provided outside a clean environment, and anon-contacting seal is provided between the clean environment and anexternal environment.

A characteristic of a non-contacting seal device is that it is able toseparate two spaces in a non-contacting manner. In an individualapparatus to which a non-contacting seal device is applied (hereinafter,frequently referred to simply as “the apparatus”), such a characteristicof a non-contacting seal device is a merit when the seal device performsa sealing function in a normal operating condition. However, pressureconditions of the apparatus are subject to change at a time of startingor stopping the seal device or after stopping the seal device, dependingon the method employed for operating the seal device. From the viewpointof a time required for starting the individual apparatus, a risk ofcontamination when stopping the apparatus and maintaining a desireddegree of cleanliness, it is necessary to take into account a way inwhich the apparatus is affected by the method for operating the sealdevice.

Referring to FIG. 1, explanation is made with regard to how theapparatus is affected by the method for operating the seal device, atthe time of starting or stopping the seal device and after stopping theseal device. First, explanation is made with regard to the apparatus atthe time of starting the seal device. As shown in FIG. 1, the sealdevice comprises a sealing passage 3 having a small cross-sectional areawhich connects a first space 1 and a second space 2. In an initialstate, the first space 1, the second space 2 and the sealing passage 3are maintained at the same pressure, for example, at atmosphericpressure. The first space 1 is a vacuum chamber which is to be broughtinto a high-vacuum condition for, for example, processing a substratefor manufacturing a semiconductor device. The second space 2accommodates a transport mechanism for transporting substrates, and hasa low degree of cleanliness as compared to the first space 1. The secondspace 2 may be an atmospheric environment in a clean room. In thisstate, the seal device is started. However, the following problems mayarise, depending on the method used for starting the seal device.

[CASE 1]

In CASE 1, initially, a vacuum pump 41 in an evacuation line L1 isactuated and a valve 51 is opened, to thereby start evacuation throughthe evacuation line L1. Subsequently, a vacuum pump 42 in an evacuationline L2 is actuated and a valve 52 is opened, to thereby startevacuation through the evacuation line L2. In a normal operatingcondition of the seal device, the pressure relationship between thefirst space 1, the second space 2 and the sealing passage 3 isrepresented by P1<P3<P2 (in terms of a degree of vacuum, V1>V3>V2),wherein P1, P2 and P3 represent the pressures in the first space 1, thesecond space 2 and the sealing passage 3, respectively, and V1, V2 andV3 represent the degrees of vacuum in the first space 1, the secondspace 2 and the sealing passage 3, respectively. In a transient stateafter the start of evacuation through the evacuation line L1 by openingthe valve 51, the relationship P1<P3<P2 or P1<P3=P2 (for example, P1 isseveral Torr, P3 is a value between atmospheric pressure and severalhundred Torr and P2 is atmospheric pressure) is established. In thisstate, a considerable amount of gas flows from the second space 2 intothe first space 1.

Thereafter, when evacuation through the evacuation line L2 is started byopening the valve 52, most of the gas flowing from the second space 2 isintroduced into the evacuation line L2 and does not flow into the firstspace 1. Consequently, the pressure relationship P1<P3<P2 in a normaloperating condition (for example, P1 is 1E-6 Torr, P3 is 1E-3 Torr andP2 is atmospheric pressure) is established, and the seal device startsto operate in a normal operating condition.

Thus, in the above operation for starting the seal device, aconsiderable amount of gas flows from the second space 2 into the firstspace 1. Therefore, the degree of cleanliness of the first space 1lowers. For example, when air having a humidity of 50% flows from thesecond space 2 into the first space 1, the ultimate degree of vacuum inthe first space 1 lowers. Further, if the second space 2 containsforeign matter, such matter will enter a small gap in the sealingpassage 3, and clog the sealing passage 3. The gap provided in thesealing passage 3 is generally 1 mm or less. Recently, ahigh-performance seal device adapted for sealing a gap as small as 0.005mm (=5 μm) has also been made available.

[CASE 2]

In CASE 2, the vacuum pump 42 is first actuated and the valve 52 isopened, to thereby start evacuation through the evacuation line L2.Subsequently, the vacuum pump 41 is actuated and the valve 51 is opened,to thereby start evacuation through the evacuation line L1. The pressurerelationship in a normal operating condition is P1<P3<P2 (in terms of adegree of vacuum, V1>V3>V2). In a transient state after the start ofevacuation through the evacuation line L2 by opening the valve 52, therelationship P1>P3<P2 (for example, P1 is several hundred Torr, P3 isseveral Torr and P2 is atmospheric pressure) is established. Therefore,a gas flows from the second space 2 into the sealing passage 3.

Subsequently, evacuation through the evacuation line L1 is started byopening the valve 51. In this instance, a slight amount of gas flowsfrom the second space 2 into the first space 1. Then, the pressurerelationship in a normal operating condition, that is, P1<P3<P2 (forexample, P1 is 1E-6 Torr, P3 is 1E-3 Torr and P2 is atmosphericpressure), is established, thus completing the starting operation.During the starting operation, there is a possibility that foreignmatter contained in the second space 2 may become mixed in the gas flowand clog the small gap in the sealing passage 3.

Next, explanation is made with regard to problems arising due to asequence of steps conducted for stopping the seal device. Initially, adifferential exhausting sealing function is performed in a normaloperating condition. The pressure relationship in this condition isP1<P3<P2 (in terms of a degree of vacuum, V1>V3>V2) For example, P1 is1E-6 Torr, P3 is 1E-3 Torr and P2 is atmospheric pressure.

[CASE 3]

In CASE 3, the valve 51 and the valve 52 are closed at the same time. Inthis case, the first space 1 is subject to a phenomenon that a cracksuch as a sealing passage 3 is created in a wall defining a vacuumchamber. That is, a gas in the second space 2 vigorously flows throughthe sealing passage 3 into the first space 1. Thus, a considerableamount of gas flows from the second space 2 into the first space 1, thuslowering a degree of cleanliness of the first space 1. For example, whenair having a humidity of 50% flows from the second space 2 into thefirst space 1, the ultimate degree of vacuum in the first space 1lowers. Further, if the second space 2 contains foreign matter, suchmatter will enter a small gap in the sealing passage 3, and clog thesealing passage 3.

[CASE 4]

In CASE 4, the valve 52 is first closed, and then the valve 51 isclosed. In this case also, the first space 1 is subject to a phenomenonthat a crack such as a sealing passage 3 is created in a wall definingthe vacuum chamber. That is, a gas in the second space 2 vigorouslyflows through the sealing passage 3 into the first space 1. This impartsto the vacuum pump 41, which draws a high vacuum in the first space 1,an effect similar to that of entry of the atmosphere. When use is madeof a turbomolecular pump, of which turbine blades are rotated atultrahigh speed and strike molecules, an excessive amount of externalforce acts on the blades, thus resulting in the possibility of breakageof the blades.

Thus, in CASE 4, a considerable amount of gas flows from the secondspace 2 into the first space 1, thus lowering the degree of cleanlinessof the first space 1. For example, when air having a humidity of 50%flows from the second space 2 into the first space 1, the ultimatedegree of vacuum in the first space 1 lowers. Further, if the secondspace 2 contains foreign matter, such matter will enter a small gap inthe sealing passage 3, and clog the sealing passage 3.

[CASE 5]

When the valve 51 is first closed and the valve 52 is then closed, aconsiderable amount of gas flows from the second space 2 into the firstspace 1 through the gap in the sealing passage 3 until the pressurerelationship P1=P3 or P1>P3 is established. Therefore, the degree ofcleanliness of the first space 1 lowers. For example, when air having ahumidity of 50% flows from the second space 2 into the first space 1,the ultimate degree of vacuum in the first space 1 lowers. Further, ifthe second space 2 contains foreign matter, such matter will enter asmall gap in the sealing passage 3, and clog the sealing passage 3.

Next, explanation will be made with regard to how the apparatus isaffected by the sealing passage 3 after stopping the seal device.

[CASE 6]

In each of CASES 3, 4 and 5, a gas flows from the second space 2 intothe first space 1. If such a state is permitted, the first space 1 willbe brought into a state similar to that of a vacuum chamber opened andexposed to a gas in an external environment, such as air in a cleanroom. In this case, if the air in a clean room is a moist gas having ahumidity of about 50%, an inner surface of a wall defining the firstspace 1 is exposed to such a moist gas. Therefore, the ultimate degreeof vacuum in the first space 1 when reproducing a vacuum becomes low. Inother words, it is difficult to achieve the degree of vacuum for whichthe apparatus is set, and therefore the time for restarting theapparatus is markedly prolonged.

[CASE 7]

When dry gas is fed into the first space 1 in order to maintain thepressures in the first space 1 and the second space 2 at the same level,because the first space 1 and the second space 2 are communicatedthrough the sealing passage 3, if the gas in the second space 2 has ahigh humidity, the humidity of the entire space including the firstspace 1 and the second space 2 moves towards a state of equilibrium.That is, the gas in the first space 1 acts like a dry sponge absorbing awater component of the gas occupying the second space 2. Consequently,water is adsorbed on the inner wall surface defining the first space 1.Therefore, the ultimate degree of vacuum in the first space 1 whenreproducing a vacuum becomes low. In other words, it is difficult toachieve the degree of vacuum for which the apparatus is set, andtherefore a time for restarting the apparatus is markedly prolonged.

After stopping the seal device, if the first space 1 is filled with airhaving a humidity of 50% and the apparatus is restarted 1 day afterstopping of the seal device, an operation for reproducing a vacuum mustbe conducted for 1 month to achieve a set degree of vacuum in the firstspace 1.

Generally, in a substrate processing apparatus, a substrate is loaded ona stage device, and moved so that a specific region on the substrate'ssurface is located at a predetermined position and processed.

The stage device includes a movable base and a stationary base, and aguide element and a drive element. To move a substrate loaded on themovable base, a control command is applied to the drive element, whichimparts a thrust force to the movable base. Thus, the movable base ismoved, while being guided by the guide element.

As a guide element, a rolling guide element has been conventionallyused. The rolling guide element requires use of a lubricant, and aneffective means to suppress generation of dust and a release of gasaccompanying a rolling motion of the guide element is studied.

As a drive element, a rotary motor or a linear motor, which convertselectric energy to kinetic energy, is employed. A rotary motor is usedin combination with a magnetic fluid seal. This combination has a meritsuch that the motor can be provided outside a vacuum chamber in which asubstrate is provided. That is, the motor can be used in an atmosphericenvironment, and the type of the motor can therefore be selected from awide range.

However, the use of a rotary motor in combination with a magnetic fluidseal has a demerit such that (a) the life of the magnetic fluid sealbecomes short. The life of the magnetic fluid seal is in inverseproportion to the degree of vacuum. That is, the higher the degree ofvacuum created in the vacuum chamber, the shorter the life of themagnetic fluid seal. Another demerit is that (b) it is essential toprovide a mechanism for converting a rotary motion to a linear motion.Thus, it is not possible to effect a smooth linear motion due torattling or friction of the converting mechanism.

Therefore, in recent years, there has been an increasing tendency to usea linear motor, which does not require use of a converting mechanism,and therefore has no demerit (b). However, there is no vacuum sealsuitable for use with a linear motor. Therefore, it has been desired toemploy a linear motor which can be suitably used within a vacuumenvironment, that is, one which is free from problems, such as (c) arelease of gas, (d) generation of heat and (e) generation of dust.However, the problems of a release of gas and generation of heat cannotbe completely avoided in practice. Therefore, a conventional substrateprocessing apparatus such as that shown in FIG. 2 is employed.

In FIG. 2, reference 1 a denotes a first space or vacuum chamber; 2 asecond space or vacuum chamber; 4 a housing defining the first andsecond vacuum chambers 1 and 2; 3 a a passage formed by a wall 6 betweenthe first vacuum chamber 1 and the second vacuum chamber 2; 11 a stagedevice provided in the first vacuum chamber 1 and comprising astationary base 12 and a movable base 13 movably supported on thestationary base 12 by a rolling mechanism 14; 15 a drive device providedin the second vacuum chamber 2 and connected to the movable base 13through a connecting member 16 extending through the passage 3 a; and 17an electron beam generating column for processing a substrate S loadedon the movable base 13. The passage 3 a provides a restricted portionwhich connects the first space or vacuum chamber 1 a and the secondspace or vacuum chamber 2 a. The first vacuum chamber 1 a and the secondvacuum chamber 2 a are evacuated by means of individual vacuum pumps 18and 19, such as ion pumps. The pressure in the first vacuum chamber 1 aand the pressure in the second vacuum chamber 2 a are controlled so asto satisfy the relationship P1<P2<P0, wherein P1 and P2 represent thepressure in the first vacuum chamber 1 a and the pressure in the secondvacuum chamber 2 a, respectively, and P0 represents atmosphericpressure. (If P1, P2 and P0 are replaced by the corresponding degrees ofvacuum DV1, DV2 and DV0, the relationship DV1>DV2>DV0 is established.)The purpose of this arrangement is to protect the first vacuum chamber 1a from gas, heat and dust generated from the drive element. It should benoted that in the present specification, the term “a vacuum chamber”does not mean a chamber in an absolute vacuum, but rather a chamberhaving a low pressure such as that which is referred to as a “vacuum” inthe related art.

FIG. 3 shows another example of a conventional substrate processingapparatus. In FIG. 3, the same parts or portions as those shown in FIG.2 are designated by the same reference numerals as used in FIG. 2, andexplanation thereof is omitted. In the substrate processing apparatus inFIG. 3, a bellows type seal device 21 is provided in a passage 5 whichcorresponds to the passage 3 a forming the restricted portion in FIG. 2,so as to prevent a flow of gas from the second vacuum chamber 2 a to thefirst vacuum chamber 1 a. However, a reaction force and vibrationsproduced by expansion and contraction of the bellows interfere with asmooth movement of a substrate. This can be avoided by using a fluorineresin, which is flexible and can be suitably used in a vacuum condition,for the bellows. When a difference between the pressures P1 and P2 issmall, even a bellows made of a flexible material is capable of servingas a pressure bulkhead.

FIG. 4 shows a further example of a conventional substrate processingapparatus. In FIG. 4, the same parts or portions as those shown in FIGS.2 and 3 are designated by the same reference numerals as used in FIGS. 2and 3, and explanation thereof is omitted. In the substrate processingapparatus of FIG. 4, the second space is changed from a vacuum chamber 2a shown in FIG. 2 to an atmospheric environment under atmosphericpressure P0 in which the drive device 15 (such as a linear motor) isdisposed. Since the second vacuum chamber 2 a is replaced with anatmospheric environment, the bellows type seal device 21 which alsoserves as a pressure bulkhead is required to withstand a differentialpressure as high as 1 kg/cm². Therefore, a bellows made of a flexiblematerial such as a fluorine resin cannot be used, and effects of areaction force and vibrations produced by a bellows cannot be avoided.However, a countermeasure for generation of heat by the drive element(i.e., cooling) can be easily taken, and a vacuum system having a simpleconstruction can be employed.

FIG. 5 shows a further example of a conventional substrate processingapparatus. In FIG. 5, the same parts or portions as those shown in FIGS.2 to 4 are designated by the same reference numerals as used in FIGS. 2to 4, and explanation thereof is omitted. In FIG. 5, the drive device 15(such as a linear motor) is provided in an atmospheric environment, anda non-contacting seal device (a differential exhausting or vacuum sealdevice) 25 is provided in the passage 3 a in which the connecting member16 connecting the stage device 11 and the drive device 15 extends. Thenon-contacting seal device 25 provides a seal between the first vacuumchamber 1 and the atmospheric environment. The non-contacting sealdevice 25 comprises a plurality of (three in this embodiment) vacuumgrooves 26 formed in an inner circumferential surface of the wall 6 inthe passage 3 a. The vacuum grooves 26 are individually connected toevacuation lines. The vacuum grooves 26 are evacuated through theevacuation lines so as to produce individual vacuum pressures P3, P4 andP5 in the vacuum grooves 26 so that the relationship P0>P3>P4>P5>P1 isestablished (if P0, P3, P4, P5 and P1 are replaced by the correspondingdegrees of vacuum DV0, DV3, DV4, DV5 and DV1, the relationshipDV0<DV3<DV4<DV5<DV1 is established). In this arrangement, there is noneed to evacuate the second space 2 a, and the apparatus can be reducedin size. Further, the non-contacting seal device 25 is employed, insteadof the bellows type seal device 21 in FIG. 4. Therefore, the problems ofa reaction force and vibrations produced by expansion and contraction ofthe bellows can be avoided.

In this arrangement, however, when the non-contacting seal device 25stops operating, atmospheric pressure is introduced into the firstvacuum chamber 1 through the passage 3 a, so that the pressure in thefirst vacuum chamber 1 becomes substantially equal to atmosphericpressure. That is, the vacuum of the first vacuum chamber 1 cannot bemaintained. Therefore, when the apparatus stops operating in the eventof emergency, for example, a power failure, a vacuum must be reproducedin the first vacuum chamber 1 a, and the time required for reproducing avacuum becomes considerably long, depending on the characteristics ofthe gas flowing into the first vacuum chamber 1.

Therefore, a substrate processing apparatus as shown in FIG. 6 isproposed. The apparatus of FIG. 6 comprises a first space or vacuumchamber 1 a in which the stage device 11 is provided, and a second spaceor chamber 7 (pressure: P7) in which the drive device 15 (such as alinear motor) is provided. The space 7 is separated from an ambientatmosphere by a cover 8 and from the first vacuum chamber 1 a by thewall 6 and the non-contacting seal device (differential exhausting sealdevice) 25. The non-contacting seal device 25 is provided in the passage3 a in which the connecting member 16 connecting the stage device 11 andthe drive device 15 extends. The non-contacting seal device 25 in FIG. 5has the same structure and performs the same function as thenon-contacting seal device 25 shown in FIG. 4. A plurality of (three inthis embodiment) vacuum grooves 26 are formed in the innercircumferential surface of the wall 6 in the passage 4 and areindividually connected to the evacuation lines L6-1, L6-2 and L6-3. Thevacuum grooves 26 are evacuated so as to produce individual vacuumpressures P3, P4 and P5, which satisfy the relationshipP7>P6-3>P6-2>P6-1>P1 (if P7, P3, P4, P5 and P1 are replaced by thecorresponding degrees of vacuum DV7, DV3, DV4, DV5 and DV1, therelationship DV7<DV3<DV4<DV5<DV1 is established) In this arrangement,atmospheric pressure is not directly introduced into the first vacuumchamber 1, even when the non-contacting seal device 25 stops operating.

In the above-mentioned arrangements, the movable base 13 of the stagedevice 11 is movably supported by the rolling mechanism 14.Theoretically, it is impossible to prevent generation of dust in therolling mechanism 14.

Therefore, in a substrate processing apparatus shown in FIG. 7, a stagedevice 31 having no rolling mechanism is provided. A movable base 33 ofthe stage device 31 is supported, on one side, by the connecting member16, while the connecting member 16, and hence the movable base 33, aresupported by using a non-contacting type guide element [such as a staticbearing (an air bearing)] 35. The non-contacting type guide element 35is provided in the passage 3 a at a position adjacent to thenon-contacting seal device 25 and on a side of the drive device 15.Thus, there is no problem of generation of dust. Further, because thenon-contacting seal device 25 is used, it is possible to avoidgeneration of dust in a seal portion, and problems of a reaction forceand vibrations produced by a bellows can also be avoided. In thearrangement of FIG. 7, the space in which the drive device 15 is placedis an atmospheric environment. The movable base 33 of the stage device31 is supported on one side, but this does not limit the arrangement ofFIG. 7. Incidentally, in the arrangement of FIG. 7, relative horizontalpositions of a reflecting mirror 41 provided on the movable base 33 onwhich the substrate S is loaded and a reflecting mirror 42 provided on aside of the electron beam generating column 17 are measured by a laserinterferometer 43. The pressure relationship in this arrangement isP0<PB>P6-3>P6-2>P6-1>P1, wherein PB represents an internal pressure ofthe static bearing 35, and P6-3, P6-2 and P6-1 represent the pressuresin the vacuum grooves 26 of the non-contacting seal device 25 which areevacuated through the evacuation lines. If P0, PB, P6-3, P6-2, P6-1 andP1 are replaced by the corresponding degrees of vacuum DV0, DVB, DB6-3,DB6-2, DV6-1 and DV1, the relationship DV1>DV6-1>DV6-2>DV6-3>DVB<DV0 isestablished. DVB represents the degree of vacuum of the static bearing35.

In the arrangement of FIG. 7, only one vacuum chamber 1 is provided.Therefore, a vacuum system having a simple construction can be used, andthe size of the apparatus can be reduced. However, as in the case ofFIG. 5, when the non-contacting seal device 25 stops operating,atmospheric pressure is inevitably introduced into the first vacuumchamber 1 through the passage 4 and therefore, the pressure in the firstvacuum chamber 1 becomes substantially equal to atmospheric pressure.That is, the vacuum of the first vacuum chamber 1 cannot be maintained.Consequently, a considerable amount of time is required for reproducinga vacuum.

In a substrate processing apparatus shown in FIG. 8, differing from theapparatus of FIG. 7, a space in which the drive device 15 (such as alinear motor) is provided is defined, by the cover 8, as the secondspace or chamber 7 which is separated from an ambient atmosphere by thecover 8 and from the first vacuum chamber 1 by the wall 6 and thenon-contacting seal device 25. In this apparatus, the pressurerelationship is P7<PB>P6-3>P6-2>P6-1>P1. If P7, PB, P6-3, P6-2, P5-1 andP1 are replaced by the corresponding degrees of vacuum DV7, DVB, DV6-3,DV6-2, DV6-1 and DV1, the relationship DV1>DV6-1>DV6-2>DV6-3>DVB<DV7 isestablished.

The drive device 15 is not limited to a linear motor. For example, acylinder device may be used. When a cylinder device is used as the drivedevice 15, care must be taken to avoid 1) leakage of a differentialfluid from a seal portion (a release of gas), 2) generation of dust inthe seal portion and 3) a temperature change caused by compression andexpansion of a fluid.

In a conventional technique shown in FIG. 2, a device (such as a drivedevice) which causes a release of gas, and generation of dust and heat,is provided in the second space or vacuum chamber 2 a, while a substrateis provided in the first space or vacuum chamber 1 a. A pressuredifferential between the first vacuum chamber 1 a and the second vacuumchamber 2 a is determined so as to satisfy the relationship P1<P2 (Interms of a degree of vacuum DV, DV1>DV2). With respect to the reason forthis determination, it is considered as follows. With respect to thefirst vacuum chamber 1 a, a high degree of vacuum is required to beproduced, because a clean environment must be formed in a space in whicha substrate is provided. With respect to the second vacuum chamber 2 ain which a device that causes a deterioration in the second vacuumchamber 2 a is provided, a release of gas from the device cannot beavoided, and cleanliness of the second vacuum chamber 2 is not as highlynecessary as compared to the first vacuum chamber 1 a. Therefore, thevacuum of the second vacuum chamber 2 a may be lower than that of thefirst vacuum chamber 1 a.

However, leakage of gas inevitably occurs between two chambers havingdifferent pressures. That is, there is a possibility that part of a gasgenerated in the second vacuum chamber 2 a flows into the first vacuumchamber 1 a, which is required to be clean.

Further, in practice, there is a problem of a reverse flow or diffusionof gas derived from an oil component from an oil-sealed rotary vacuumpump, an oil component remaining in parts or ducts of a vacuum system,and a lubricant used for the vacuum pump. When the above pressurerelationship P1<P2 (in terms of a degree of vacuum DV, DV2<DV1) isestablished in the apparatus of FIG. 2, a gas which has been introducedinto the second vacuum chamber 2 a due to the above-mentioned reverseflow or diffusion is further introduced from the second vacuum chamber 2a into the first vacuum chamber 1 a.

In a conventional technique shown in FIG. 6, the non-contacting sealdevice (differential exhausting seal device) 25 is employed as a sealdevice. When a gap between the connecting member 16 and the innercircumferential surface of the wall 6 defining the passage 3 a isindicated by g0, the value of g0 is about 5 to 50 μm. From the viewpointof reducing a load on the vacuum system, the value of g0 should beminimized. This means that a sealing performance changes due tovariations in the value of g0 resulting from pressure variations (in arange between atmospheric pressure and a vacuum pressure) in the vacuumchamber. To prevent such variations in the value of g0, it is necessaryto form a rigid structure by, for example, increasing a wall-thicknessof the housing 3 defining the vacuum chamber. However, this leads to aproblem, such as a large weight of the apparatus.

The same problem is encountered in the apparatus shown in FIG. 8.Further, in the apparatus of FIG. 8 in which the non-contacting typeguide element 35 is used, a guiding performance also changes due tovariations in the value of gap g0. Therefore, a problem occurs, suchthat orthogonality of the movable base 33 of the stage device 31 isimpaired, or the substrate's surface is vertically displaced.

FIG. 9 indicates the pressure relationship established in the apparatusin which the differential exhausting seal device 25 (of a type havingthree vacuum grooves) is provided between the first vacuum chamber 1 aand the second chamber or space 7. P7 may be atmospheric pressure. Thegas flowing towards the first vacuum chamber 1 a (in which a substrateis processed) due to a pressure differential between the first vacuumchamber 1 a and the second chamber or space 7 is sucked through thethree vacuum grooves, thus preventing the gas from flowing into thefirst vacuum chamber 1 a. Normally, the pressure distribution(relationship) is P7>P6-3>P6-2>P6-1>P1. Therefore, a slight amount ofgas flows from a region under pressure P5 into the first vacuum chamber1 a under pressure P1. It is most undesirable to allow a reverse flow ordiffusion of gas derived from an oil component from an oil-sealed rotaryvacuum pump, an oil component remaining in parts or ducts of a vacuumsystem, and a lubricant used for the vacuum pump. In many cases, ahigh-vacuum pump having a large volume is used so that the first vacuumchamber 1 a has the highest degree of vacuum (P1 becomes the lowestpressure). However, this high-vacuum pump causes a reverse flow of anoil component from the oil-sealed rotary vacuum pump for the vacuumgroove of the pressure P6-1, an oil component remaining in parts orducts of the vacuum system, and a vapor of a lubricant used for thevacuum pump.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a seal device, whichavoids the risk of contamination of a space required to have highcleanliness and deposition of water on an inner wall surface of thespace, and which is capable of reducing a time required for reproducinga vacuum. It is another object of the present invention to provide amethod for operating the seal device.

It is a further object of the present invention to provide a substrateprocessing apparatus comprising a first vacuum chamber in which asubstrate loaded on a stage device is processed and a second vacuumchamber in which a drive device for driving the stage device isprovided, wherein the pressure in the second vacuum chamber iscontrolled to be lower than that in the first vacuum chamber, to therebysolve the above-mentioned problems.

It is a further object of the present invention to provide a substrateprocessing apparatus comprising a first chamber in which a substrateloaded on a stage device is processed and a second chamber in which adrive device for driving the stage device is provided, wherein the firstchamber is maintained in a vacuum and a non-contacting seal device isprovided between the first chamber and the second chamber, andrespective pressures in the first and second chambers are controlled inrelation to an operating condition of the non-contacting seal device, tothereby solve the above-mentioned problems.

It is a still further object of the present invention to provide asubstrate processing apparatus comprising a first chamber in which asubstrate loaded on a stage device is processed and a second chamber inwhich a drive device for driving the stage device is provided, whereinthe first chamber is maintained in a vacuum, and a differential vacuumseal device comprising a plurality of vacuum grooves is provided betweenthe first chamber and the second chamber, to enable the pressures in thevacuum grooves to be appropriately controlled, thereby solving theabove-described problems.

The present invention provides a seal device comprising a sealingpassage which allows communication between a first space and a secondspace, and evacuation lines individually connected to the first spaceand the sealing passage, wherein a gas feed line for feeding dry gas isconnected to the sealing passage.

In the above-mentioned seal device, a gas feed line for feeding dry gasmay be connected to the sealing passage, and the timing ofstarting/stopping the feeding of dry gas through the gas feed line andthe timing of starting/stopping evacuation through the evacuation linesconnected to the first space and the sealing passage may be controlled.By this arrangement, it is possible to prevent a considerable amount ofgas from flowing from the second space having a low degree ofcleanliness to the first space having a high degree of cleanliness. Itis also possible to suppress deposition of water on an inner wallsurface of the first space, which is required to have high cleanliness,thus reducing the time required for regenerating a vacuum.

In the above-mentioned seal device, the degree of cleanliness or vacuumof the first space and the degree of cleanliness or vacuum of the secondspace may be different so that the first space has a high degree ofcleanliness or vacuum and the second space has a low degree ofcleanliness or vacuum, and the gas feed line may be connected to thesealing passage at a position between the second space and theevacuation line located closest to the second space.

As described above, in the present invention, the gas feed line may beconnected to the sealing passage at a position between the second spaceand the evacuation line located closest to the second space. With thisarrangement, a flow of gas from the second space having low cleanlinessor vacuum to the first space having high cleanliness or vacuum can beeffectively suppressed.

The present invention provides a method for operating theabove-mentioned seal device, wherein the seal device is started usingthe following sequence of steps (1) to (4):

(1) feeding dry gas through the gas feed line;

(2) controlling a flow rate of the dry gas fed through the gas feed lineso that a pressure at a gas feed port of the gas feed line formed in thesealing passage is maintained at a level equal to or higher than apressure in the second space;

(3) starting evacuation through the evacuation line for the sealingpassage; and

(4) starting evacuation through the evacuation line for the first space.

In the above-mentioned method, the seal device is started using theabove sequence of steps (1) to (4), to thereby prevent a considerableamount of gas from flowing from the second space into the first space.Therefore, it is possible to prevent a lowering of cleanliness of thefirst space, which would otherwise result from a flow of gas from thesecond space having low cleanliness into the first space having highcleanliness. Further, it is possible to avoid a situation that due to ahigh humidity of the gas flowing into the first space, water isdeposited on an inner wall surface of the first space thereby loweringthe ultimate degree of vacuum. Further, it is possible to preventclogging of the sealing passage which would otherwise result from entryof foreign matter contained in the second space into a small gap in thesealing passage.

The present invention also provides a method for operating theabove-mentioned seal device, wherein the seal device is stopped usingthe following sequence of steps (1) to (4):

(1) feeding dry gas through the gas feed line;

(2) controlling a flow rate of the dry gas fed through the gas feed lineso that a pressure at a gas feed port of the gas feed line formed in thesealing passage is maintained at a level equal to or higher than apressure in the second space;

(3) stopping evacuation through the evacuation line for the first space;and

(4) stopping evacuation through the evacuation line for the sealingpassage.

In the above-mentioned method, the seal device is stopped using theabove sequence of steps (1) to (4), to thereby prevent a considerableamount of gas from flowing from the second space into the first space.Therefore, it is possible to prevent a lowering of cleanliness of thefirst space, which would otherwise result from a flow of gas from thesecond space having low cleanliness into the first space having highcleanliness. Further, it is possible to avoid a situation where water isdeposited on an inner wall surface of the first space due to a highhumidity of the gas flowing into the first space. Therefore, a timerequired for reproducing a vacuum can be made relatively short. Further,it is possible to prevent the sealing passage from becoming clogged dueto entry of foreign matter contained in the second space into a smallgap in the sealing passage.

The present invention further provides a method for operating theabove-mentioned seal device, wherein after stopping the seal device, drygas is fed through the gas feed line and a flow rate of the dry gas fedthrough the gas feed line is controlled so that a pressure at a gas feedport of the gas feed line formed in the sealing passage is maintained ata level equal to or higher than a pressure in the second space.

In the above-mentioned method, after stopping of the seal device, drygas is fed through the gas feed line and a flow rate of the dry gas fedthrough the gas feed line is controlled so that a pressure at a gas feedport of the gas feed line formed in the sealing passage is maintained ata level equal to or higher than a pressure in the second space. By usingthis arrangement, it is possible to prevent a lowering of cleanliness ofthe first space due to a flow of gas from the second space having lowcleanliness into the first space having high cleanliness. Further, it ispossible to avoid deposition of water on an inner wall surface of thefirst space due to a high humidity of the gas flowing into the firstspace. Therefore, the time required for regenerating a vacuum can bemade relatively short.

In the above-mentioned method for operating the seal device, the dry gasfed through the gas feed line may be a gas comprising substantially thesame components as air and having a humidity of 5% or less.

As described above, in the present invention, the dry gas fed throughthe gas feed line may comprise substantially the same components as airand have a humidity of 5% or less. With this arrangement, the amount ofdeposition of water on an inner wall surface of the first space isreduced. Further, workers can enter the second space without anydifficulties.

The present invention further provides a substrate processing apparatuscomprising a first vacuum chamber in which a stage device is providedand a substrate loaded on the stage device is processed, and a secondvacuum chamber provided separately from the first vacuum chamber; adrive element for driving the stage device is provided in the secondvacuum chamber; with a pressure P1 in the first vacuum chamber and apressure P2 in the second vacuum chamber being controlled so as tomaintain a relationship P1≧P2.

In the above-mentioned substrate processing apparatus, although a flowof gas from the first vacuum chamber into the second vacuum chamberoccurs, gas generated in or released into the second vacuum chamber isprevented from flowing into the first vacuum chamber in which asubstrate is processed. In this way, it is possible to preventcontamination of substrates, reflecting mirrors or marks.

The present invention further provides a substrate processing apparatuscomprising a first chamber in which a stage device is provided, and inwhich a substrate loaded on the stage device is processed; with a secondchamber being provided separately from the first chamber. A driveelement for driving the stage device is provided in the second chamber,and the first chamber is maintained in a vacuum, with a non-contactingseal device being provided between the first chamber and the secondchamber. The second chamber is capable of being selectively connected toa supply source of dry gas; and a pressure in the second chamber iscontrolled to be equal to or approximate to atmospheric pressure bysupplying and discharging the dry gas.

In the above mentioned substrate processing apparatus according to thesecond embodiment of the present invention, even when the non-contactingseal device stops operating, there is no gas flow from an externalenvironment, such as a clean room, into the vacuum chamber. Thus, thesubstrate processing apparatus is able to adapt in a case that anemergency stop of the seal device occurs, and the time for regeneratinga vacuum in the vacuum chamber can thus be reduced. Further, there is noneed to increase a wall-thickness of a cover or a housing for a chamberso as to maintain a predetermined small gap in the non-contacting sealportion. Consequently, the apparatus can be reduced in size, and madelightweight in construction.

The present invention further provides a substrate processing apparatuscomprising a first chamber in which a stage device is provided and asubstrate loaded on the stage device is processed, with a second chamberbeing provided separately from the first chamber. A drive element fordriving the stage device is provided in the second chamber, and thefirst chamber is maintained in a vacuum, and a non-contacting sealdevice is provided between the first chamber and the second chamber. Thesecond chamber is capable of being selectively connected to a supplysource of dry gas. When the non-contacting seal device is operated whilethe stage device is being driven, a pressure in the second chamber iscontrolled to be equal to or approximate to atmospheric pressure bysupplying and discharging the dry gas. During a period that thenon-contacting seal device is not operated, the second chamber isdisconnected from the supply source of dry gas, and discharge of the gasfrom the second chamber is stopped.

In the above above-mentioned substrate processing apparatus, it ispossible to prevent a reverse flow or diffusion of gas from a vacuumsystem of the differential vacuum seal device, which would otherwiseresult in contamination of the first vacuum chamber. Consequently,cleanliness of the first vacuum chamber can be maintained at asatisfactory level, and the apparatus does not need frequent cleaning ormaintenance.

The present invention further provides a substrate processing apparatuscomprising a first chamber in which a stage device is provided and asubstrate loaded on the stage device is processed, and a second chamberprovided separately from the first chamber. A drive element for drivingthe stage device is provided in the second chamber. The first chamber ismaintained in a vacuum and a differential vacuum seal device comprisinga plurality of vacuum grooves is provided between the first chamber andthe second chamber, with a vacuum groove located closest to the firstchamber having an internal pressure lower than or equal to a pressure inthe first chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an example of a conventional seal device.

FIG. 2 is a schematic cross-sectional view of an example of aconventional substrate processing apparatus comprising two vacuumchambers.

FIG. 3 is a schematic cross-sectional view of another example of aconventional substrate processing apparatus comprising two vacuumchambers.

FIG. 4 is a schematic cross-sectional view of an example of aconventional substrate processing apparatus comprising one vacuumchamber.

FIG. 5 is a schematic cross-sectional view of another example of aconventional substrate processing apparatus comprising one vacuumchamber.

FIG. 6 is a schematic cross-sectional view of a conventional substrateprocessing apparatus comprising a vacuum chamber for processing asubstrate, and a chamber provided separately from the vacuum chamber.

FIG. 7 is a schematic cross-sectional view of an example of a substrateprocessing apparatus in which a stage device having no rolling typesupport mechanism is provided.

FIG. 8 is a schematic cross-sectional view of another example of asubstrate processing apparatus in which a stage device having no rollingtype support mechanism is provided.

FIG. 9 is a graph indicating the pressure relationship with respect totwo vacuum chambers and vacuum grooves of a differential vacuum sealdevice provided therebetween.

FIG. 10 is a diagram showing an example of a seal device of the presentinvention.

FIG. 11 is a diagram showing another example of a seal device of thepresent invention.

FIG. 12 is a diagram showing a further example of a seal device of thepresent invention.

FIG. 13 is a schematic cross-sectional view of a substrate processingapparatus comprising a vacuum chamber according to an embodiment of thepresent invention.

FIG. 14 is a schematic cross-sectional view of a substrate processingapparatus comprising a vacuum chamber according to another embodiment ofthe present invention.

FIG. 15 is a graph indicating the pressure relationship with respect toa vacuum chamber, a chamber or space, and vacuum grooves of adifferential vacuum seal device provided therebetween.

DETAILED DESCRIPTION OF THE INVENTION

Hereinbelow, embodiments of the present invention are explained, withreference to FIGS. 10 to 15. As has been described, the problems arisingat the time of starting the seal device are such that: (1) a gasoccupying the second space 2, which has a lower degree of cleanlinessthan the first space 1, flows into the first space 1, resulting in alowering of cleanliness of the first space 1; (2) due to a high humidityof the gas flowing from the second space 2, water is deposited on aninner surface of a wall defining the first space 1, thus lowering theultimate degree of vacuum in the first space 1; and (3) foreign matterenters a narrow gap in the sealing passage 3, and clogs the sealingpassage 3.

FIG. 10 is a diagram showing a principle of a seal device of the presentinvention. This seal device is the same as the seal device shown in FIG.1, in that the sealing passage 3 is provided between the first space 1and the second space 2, the evacuation line L1 provided with the valve51 and the vacuum pump 41 is connected to the first space 1, theevacuation line L2 provided with the valve 52 and the vacuum pump 42 isconnected to the evacuation line L2, and a gas feed line L3 providedwith a valve 53 and a dry gas feed source (not shown) for feeding drygas DG1 is connected to the first space 1. In this example, a filter 9is provided at the sealing passage 3 on a side of the second space 2, soas to avoid the problem of entry of foreign matter contained in thesecond space 2, which is a common problem in CASES 1 and 2. By providingthe filter 9, foreign matter is prevented from becoming mixed in a gasflowing from the second space 2 into the sealing passage 3.

The seal device is arranged by providing the sealing passage 3 betweenthe first space 1 and the second space 2 and enabling the sealingpassage 3 to perform a differential vacuum sealing function. Thisarrangement is employed because a non-contact type seal is required tobe used for separating the first space 1 and the second space 2. Thereason why use of a non-contact type seal is required is that a memberconnected to an object to be moved in the first space 1 extends in thesealing passage 3, and this member is moved in a longitudinal directionof the sealing passage 3 while a predetermined gap is maintained betweenthe member and an inner wall surface defining the sealing passage 3.Therefore, the filter 9 in FIG. 2 cannot effectively prevent entry offoreign matter.

In the seal device of FIG. 11, another gas feed line L4 is provided. Thegas feed line L4 is provided with a valve 54 and a dry gas feed source(not shown) for feeding dry gas DG2 and is connected to the sealingpassage 3 between a vacuum port (or a vacuum groove) 3-1 for theevacuation line L2 and an open end 3-2 of the sealing passage 3 on aside of the second space 2.

In an initial state of this seal device, the pressure relationshipP1=P3=P4=P2 is established (wherein P3 represents a pressure at thevacuum port 3-1 in the sealing passage 3, which port is connected to theevacuation line L2, and P4 represents a pressure at a gas feed port 3-3in the sealing passage 3, which port is connected to the gas feed lineL4). To avoid entry of foreign matter into the sealing passage 3, whichoccurs in CASES 1 and 2, the seal device is started using the followingsequence of steps.

The valve 54 is opened, and the dry gas DG2 is fed through the gas feedline L4 to the sealing passage 3. As a result, the feed rate of the drygas DG2 is controlled so that the pressure relationship P4=P2,preferably P4>P2, is maintained. Thereafter, the valve 52 and/or thevalve 51 is opened, to thereby start evacuation. In this instance, thefeed rate of the dry gas DG2 through the gas feed line L4 is controlledso that the pressure relationship P4=P2 or P4>P2 is maintained.Preferably, the valve 52 is first opened to thereby start evacuationthrough the evacuation line L2. In the above sequence of steps forstarting the seal device, it is possible to prevent a considerableamount of gas from flowing from the second space 2 into the first space1. Needless to say, feeding of the dry gas 14 through the gas feed lineL4 may be stopped when the sealing passage 3 performs a sealing functionin a normal operating condition.

In an apparatus wherein foreign matter in the second space 2 does notcause any problem when it is carried by the gas flow into the sealingpassage 3, it is preferred to start the seal device in the sameoperating sequence as indicated in CASE 2. That is, it is preferred tostart the seal device by first actuating the vacuum pump 42 and openingthe valve 52, to thereby start evacuation through the evacuation lineL2, and then actuating the vacuum pump 41 and opening the valve 51, tothereby start evacuation through the evacuation line L1. By using thisoperating sequence, it is possible to prevent a considerable amount ofgas from flowing from the second space 2 into the first space 1, withoutusing the gas feed line L4 shown in FIG. 3.

Next, explanation is made with regard to how the present inventionsolves the problems arising at the time of stopping the seal device. Theproblems are caused by a considerable amount of gas flowing from thesecond space 2 into the first space 1. This can be avoided by thearrangements shown in FIGS. 10 and 11 in which a single evacuation linesuch as the evacuation line L2 is connected to the sealing passage 3.However, in practice, as shown in FIG. 12, it is advantageous to providea plurality of (three in FIG. 14) evacuation lines L5-1, L5-2 and L5-3connected to the sealing passage 3. The evacuation lines L5-1, L5-2 andL5-3 are provided with vacuum pumps 45-1, 45-2 and 45-3 and valves 55-1,55-2 and 55-3, respectively.

The seal device in FIG. 12 is arranged so as to provide differentdegrees of vacuum in vacuum ports of the respective evacuation linesL5-1, L5-2 and L5-3, thereby creating three stages of vacuum increasingtowards the first space 1. This enables a high vacuum to be easilygenerated in the first space 1. Therefore, it is preferred that the gasfeed line L4 be connected to the sealing passage 3 at a position betweenthe second space 2 and the evacuation line L5-3 located closest to thesecond space 2.

To avoid a situation where a considerable amount of gas flows from thesecond space 2 into the first space 1, the seal device shown in FIG. 4is stopped using the following sequence of steps. The pressurerelationship in a normal operating condition of the seal device isP1<P5-1<P5-2<P5-3<P2, wherein P5-1, P5-2 and P5-3, respectively,represent pressures in respective vacuum ports for the evacuation linesL5-1, L5-2 and L5-3. For example, P1 is 1E-6 Torr, P5-1 is 1E-3 Torr,P5-2 is 1E-1 Torr and P5-3 is several ten Torr and P2 is atmosphericpressure.

In a first step, the valve 54 is opened, to thereby feed the dry gas DG2through the gas feed line L4 to the sealing passage 3. When the sealdevice is arranged such that feeding of dry gas DG2 through the gas feedline L4 is constantly conducted, it is confirmed whether feeding of thedry gas DG2 is satisfactorily conducted. In a second step, the feed rateof the dry gas DG2 through the gas feed line L4 is controlled so thatthe relationship P4=P2, preferably P4>P2, is maintained even when thepressures P-1, P5-1, P5-2 and P5-3 vary. The control of the feed rate ofthe dry gas DG2 is conducted by using a controller (not shown) capableof detecting pressure.

Next, explanation is made with regard to CASE 3 (the valves 51 and 52are closed at the same time), CASE 4 (the valve 52 is first closed, andthen the valve 61 is closed) and CASE 5 (the valve 51 is first closed,and then the valve 52 is closed). The seal device of FIG. 12 can bestopped by using gradual pressure variations effected by haltingevacuation through the evacuation lines L5-1, L5-2 and L5-3 at differenttimings.

In FIG. 12, the seal device may be stopped without using the gas feedline L4. In this case, (1) the valve 51 is closed to thereby stopevacuation through the evacuation line L1, and the valve 53 is opened,to thereby feed the dry gas DG1 through the gas feed line L3 into thefirst space 1. Preferably, while regulating the flow rate of a gasdischarged through the evacuation line L1 by means of the valve 51, thefeed rate of the dry gas DG1 through the gas feed line L3 is graduallyincreased by means of the valve 53. (2) When the pressure relationshipP1=P5-1 is established, the valve 13-1 is closed, to thereby stopevacuation through the evacuation line L5-1. (3) Subsequently, when thepressure relationship P1=P5-1=P5-2 is established, the valve 13-2 isclosed, to thereby stop evacuation through the evacuation line L5-2. (4)Further, when the pressure relationship P1=P5-1=P5-2=P5-3 is obtained,the valve 13-3 is closed, to thereby stop evacuation through theevacuation line L5-3. Thus, evacuation through all the evacuation linesis stopped. (5) When the pressure relationshipP1=P5-1=P5-2=P5-3=P2=atmospheric pressure is established, the valve 53is closed, to thereby stop the feeding of the dry gas DG1 through thegas feed line L3.

However, it is preferred to use the gas feed line L4 provided with thevalve 54. In this case, as described above, the valve 54 is controlledso as to control the feed rate of dry gas through the gas feed line L4so that a pressure relationship P4=P2, preferably P4>P2, is obtained.Thereafter, the above-mentioned steps (1) to (5) are conducted. Finally,the valve 54 is closed, to thereby stop the feeding of the dry gas DG2through the gas feed line L4.

Next, description is made with regard to how the problem which arisesafter stopping the seal device is solved by the present invention. CASES6 and 7 involve a problem caused by deposition of a water component of agas from the second space 2 on an inner wall surface of the first space1. When a water component is deposited on an inner wall surface of thefirst space 1, the ultimate degree of vacuum in the first space 1 ismarkedly reduced, thus increasing a time required for restarting theentire apparatus.

To solve this problem, preferably, as shown in FIG. 12, the gas feedline L4 provided with the valve 54 is provided. After stopping of theseal device, a slight amount of dry gas is continuously flowed throughthe gas feed line L4 by control of the valve 54 so that the pressure P4is maintained at a level slightly higher than the pressure P2. When thesecond space 2 is communicated with a space which workers enter, the drygas DG2 is preferably dry air (air having a humidity of 5% or less).

In a case that the gas feed line L4 provided with the valve 54 is notprovided, the dry gas DG1 is fed through the gas feed line L3 providedwith the valve 53, while the flow rate of the dry gas DG1 is controlledsuch that the pressure P1 in the first space 1 becomes slightly higherthan the pressure P2 in the second space 2.

The substrate processing apparatus according to this embodiment issubstantially the same as that of FIG. 2, except that the pressure P1 inthe first space or vacuum chamber 1 a and the pressure P2 in the secondspace or vacuum chamber 2 a are controlled so as to satisfy therelationship P1≧P2. By this arrangement, although a gas flows from thefirst vacuum chamber 1 a into the second vacuum chamber 2 a, a gasgenerated in or released into the second vacuum chamber 2 a does notflow into the first vacuum chamber 1 a in which a substrate isprocessed. Therefore, it is possible to prevent contamination ofsubstrates, reflecting mirrors, and marks (not shown).

The substrate processing apparatus in this embodiment is shown in FIG.13. The parts or components of the substrate processing apparatus ofFIG. 13 are substantially the same as those shown in FIG. 6 and aretherefore designated by the same reference numerals as used in FIG. 6.In FIG. 13, reference numeral 1 a denotes a first space or vacuumchamber; 7 a second space or chamber separated from an ambientatmosphere by the cover 8; 4 a housing defining the first vacuum chamber1 a; 3 a a passage formed by the wall 6 between the first vacuum chamber1 a and the second chamber 7; 11 a stage device provided in the firstvacuum chamber 1 a and comprising the stationary base 12 and the movablebase 13 movably supported on the stationary base 12 by the rollingmechanism 14; 15 a drive device provided in the second space or vacuumchamber 2 a and connected to the movable base 13 through the connectingmember 16 extending through the passage 3 a; and 17 an electron beamgenerating column for processing a substrate S loaded on the movablebase 13. The first vacuum chamber 1 is evacuated by means of the vacuumpump 18, such as an ion pump. The second chamber 7 is connected to anevacuation line 45 which is controllably opened and closed by a controlvalve 46, and a dry gas feed line 47 which is controllably opened andclosed by a control valve 48. In the passage 3 a in which the connectingmember 16 connecting the stage device 11 and the drive device 15extends, there is provided a non-contacting seal device (differentialvacuum seal device) 25 having the same structure and performing the samefunction as the non-contacting seal device 25 in FIG. 6. Thenon-contacting seal device 25 includes a plurality of (three in thisembodiment) vacuum grooves 26 formed in the inner circumferentialsurface of the wall 6 in the passage 4, which are individually connectedto evacuation lines for performing evacuation at individual vacuumpressures P6-3, P6-2 and P6-1.

In FIG. 14, the parts or components of the substrate processingapparatus are substantially the same as those shown in FIG. 8, and aredesignated by the same reference numerals as used in FIG. 8. Thissubstrate processing apparatus includes the stage device 31 having norolling mechanism. The movable base 33 is supported, on one side, by theconnecting member 16. In the passage 4 in which the connecting member 16connecting the stage device 31 and the drive device 15 extends, there isprovided the non-contacting seal device (differential exhausting sealdevice) 25. The non-contacting seal device 25 includes a plurality of(three in this embodiment) vacuum or exhausting grooves 26 formed in theinner circumferential surface of the wall 6 in the passage 4, which areindividually connected to evacuation lines for performing evacuation atindividual vacuum pressures P6-3, P6-2 and P6-1. The non-contacting typeguide element [such as a static fluid pressure bearing (an air bearing)]35 is provided in the passage 3 a at a position adjacent to thenon-contacting seal device 25 and on a side of the drive device 15, soas to provide non-contacting support of the connecting member 16 (andhence the movable base 33), and eliminate the problem of generation ofdust. The non-contacting seal device 25 eliminates the problem ofgeneration of dust in the seal portion, and the problem of reactionforce and vibration produced by the seal device. The first vacuumchamber 1 a is evacuated by means of the vacuum pump 18, such as an ionpump. The second space or chamber 7 separated from an ambient atmosphereby the cover 8 is connected to the evacuation line 45 which iscontrollably opened and closed by the control valve 46 and the dry gasfeed line 47, which is controllably opened and closed by the controlvalve 48.

In the substrate processing apparatuses shown in FIGS. 13 and 14, whenthe non-contacting seal device is operated and the movable base of thestage device is moved linearly, the dry gas feed line 47 is controlledin cooperation with the evacuation line 45 so that the pressure P7 inthe second chamber 7 becomes equal to or slightly higher thanatmospheric pressure P0.

When the non-contacting seal device stops operating, the respectivecontrol valves 46 and 48 of the evacuation line 45 and the dry gas feedline 47 are closed, to thereby disconnect the second chamber 7 from theevacuation line 45 and the dry gas feed line 47. Consequently, only agas in the space 7 of the pressure P7 flows into the first vacuumchamber 1 a. In other words, the substrate in the first vacuum chamber 1a is confined to a limited space. The gas filling the space 7 of thepressure P7 comprises a dry gas (such as dry air, dry oxygen, drynitrogen, dry helium, etc.), and therefore has an extremely low moisturecontent. Therefore, even when the gas in the space 7 flows into thefirst vacuum chamber 1, a time required for regenerating a vacuum isrelatively short.

The control valve 46 may be replaced with a check valve which allows agas flowing from the space 7 within the cover 8 to the outside area ofthe cover, but prevents the gas from flowing into the space. By usingsuch a check valve, even if the pressure in the space becomes lower thanthe pressure in the outside area of the cover, the gas is prevented fromflowing into the space.

In the substrate processing apparatuses shown in FIGS. 13 and 14, of theplurality of vacuum grooves 26 of the non-contacting seal device 25, thevacuum groove at pressure P6-1 is located closest to the first vacuumchamber 1 a. In the third embodiment of the present invention, thepressure P6-1 is controlled to be lower than or equal to the pressure P1in the first vacuum chamber 1 a. By achieving this pressure relationshipP7>P6-3>P6-2>P6-1≦P1 as indicated in FIG. 11, it is possible to preventa reverse flow or diffusion of gas from the vacuum system of thedifferential vacuum seal device 25 into the first vacuum chamber 1 a.

As has been described above, the present invention has the followingadvantageous effects.

In the present invention, a gas feed line for feeding dry gas isconnected to the sealing passage, and the timing of starting/stoppingthe feeding of dry gas through the gas feed line and the timing ofstarting/stopping evacuation through the evacuation lines connected tothe first space and the sealing passage are controlled. By thisarrangement, it is possible to prevent a considerable amount of gas fromflowing from the second space having a low degree of cleanliness to thefirst space having a high degree of cleanliness. It is also possible tosuppress deposition of water on an inner wall surface of the firstspace, which is required to have high cleanliness, thus reducing thetime required for regenerating a vacuum.

In the present invention, the gas feed line may be connected to thesealing passage at a position between the second space and theevacuation line located closest to the second space. With thisarrangement, a flow of gas from the second space having low cleanlinessto the first space having high cleanliness can be effectivelysuppressed.

In the present invention, the seal device is started in a predeterminedoperating sequence as recited in claim 6, to thereby prevent aconsiderable amount of gas from flowing from the second space into thefirst space. Therefore, it is possible to prevent a lowering ofcleanliness of the first space, which would otherwise result from a flowof gas from the second space having low cleanliness into the first spacehaving high cleanliness. Further, it is possible to avoid a situationthat due to a high humidity of the gas flowing into the first space,water is deposited on an inner wall surface of the first space therebylowering the ultimate degree of vacuum. Further, it is possible toprevent clogging of the sealing passage which would otherwise resultfrom entry of foreign matter contained in the second space into a smallgap in the sealing passage.

In the present invention, the seal device is stopped in a predeterminedoperating sequence as recited in claim 7, to thereby prevent aconsiderable amount of gas from flowing from the second space into thefirst space. Therefore, it is possible to prevent a lowering ofcleanliness of the first space, which would otherwise result from a flowof gas from the second space having low cleanliness into the first spacehaving high cleanliness. Further, it is possible to avoid a situationwhere water is deposited on an inner wall surface of the first space dueto a high humidity of the gas flowing into the first space. Therefore, atime required for reproducing a vacuum can be made relatively short.Further, it is possible to prevent the sealing passage from becomingclogged due to entry of foreign matter contained in the second spaceinto a small gap in the sealing passage.

In the present invention, after stopping of the seal device, dry gas isfed through the gas feed line and a flow rate of the dry gas fed throughthe gas feed line is controlled so that a pressure at a gas feed port ofthe gas feed line formed in the sealing passage is maintained at a levelequal to or higher than a pressure in the second space. By using thisarrangement, it is possible to prevent a lowering of cleanliness of thefirst space due to a flow of gas from the second space having lowcleanliness into the first space having high cleanliness. Further, it ispossible to avoid deposition of water on an inner wall surface of thefirst space due to a high humidity of the gas flowing into the firstspace. Therefore, the time required for regenerating a vacuum can bemade relatively short.

In the present invention, the dry gas fed through the gas feed line maycomprise substantially the same components as air and have a humidity of5% or less. With this arrangement, a problem of deposition of water onan inner wall surface of the first space does not arise. Further,workers can enter the second space without any difficulties.

In the substrate processing apparatus of the invention recited in claim10, it is possible to prevent a gas released from the drive device and areverse flow or diffusion of gas from the vacuum system from beingintroduced into the first vacuum chamber in which a substrate isprovided. Thus, cleanliness of the first vacuum chamber can bemaintained at a satisfactory level. Therefore, the apparatus does notneed frequent cleaning or maintenance.

In the substrate processing apparatus according to the invention recitedin claim 11, even when the non-contacting seal device stops operating,there is no gas flow from an external environment, such as a clean room,into the vacuum chamber. Thus, the substrate processing apparatus isable to adapt in a case that an emergency stop of the seal deviceoccurs, and the time for regenerating a vacuum in the vacuum chamber canthus be reduced. Further, there is no need to increase a wall-thicknessof a cover or a housing for a chamber so as to maintain a predeterminedsmall gap in the non-contacting seal portion. Consequently, theapparatus can be reduced in size, and made lightweight in construction.

In the substrate processing apparatus according to the invention recitedin claim 12, it is possible to prevent a reverse flow or diffusion ofgas from a vacuum system of the differential vacuum seal device, whichwould otherwise result in contamination of the first vacuum chamber.Consequently, cleanliness of the first vacuum chamber can be maintainedat a satisfactory level, and the apparatus does not need frequentcleaning or maintenance.

Although the present invention has been described above in detail withreference to the drawings, the foregoing description is for explanatorypurposes and not intended to limit characteristics. It should beunderstood that the foregoing description merely illustrates andexplains preferred embodiments, and all modifications and changes withinthe scope of the spirit of the present invention are protected.

The entire disclosure of Japanese Patent Application No. 2002-103947filed on Apr. 5, 2002 and No. 2002-254082 filed on Aug. 30, 2002including specification, claims, drawings and summary is incorporatedherein by reference in its entirety.

1. A substrate processing apparatus comprising: a first vacuum chamberin which a stage device is provided and a substrate loaded on said stagedevice is processed; and a second vacuum chamber provided separatelyfrom said first vacuum chamber, a drive element for driving said stagedevice being provided in said second vacuum chamber, wherein a pressureP1 in said first vacuum chamber and a pressure P2 in said second vacuumchamber are controlled so as to maintain a relationship P1≧P2.
 2. Asubstrate processing apparatus comprising: a first chamber in which astage device is provided and a substrate loaded on said stage device isprocessed; and a second chamber provided separately from said firstchamber, a drive element for driving said stage device being provided insaid second chamber, said first chamber being maintained in a vacuum anda non-contacting seal device being provided between said first chamberand said second chamber, wherein said second chamber is capable of beingselectively connected to a supply source of dry gas, and a pressure insaid second chamber is controlled to be equal to or approximate toatmospheric pressure by supplying and discharging the dry gas.
 3. Asubstrate processing apparatus comprising: a first chamber in which astage device is provided and a substrate loaded on said stage device isprocessed; and a second chamber provided separately from said firstchamber, a drive element for driving said stage device being provided insaid second chamber, said first chamber being maintained in a vacuum anda non-contacting seal device being provided between said first chamberand said second chamber, wherein said second chamber is capable of beingselectively connected to a supply source of dry gas, and wherein whensaid non-contacting seal device is operated while said stage device isbeing driven, a pressure in said second chamber is controlled to beequal to or approximate to atmospheric pressure by supplying anddischarging the dry gas, and when said non-contacting seal device is notoperated, said second chamber is disconnected from said supply source ofdry gas, and discharge of the gas from said second chamber is stopped.4. A substrate processing apparatus according to claim 1, wherein saidfirst chamber and said second chamber are communicated through a passagein which a plurality of spaced exhausting grooves of said non-contactingseal device are formed.
 5. A substrate processing apparatus according toclaim 2, wherein said first chamber and said second chamber arecommunicated through a passage in which a plurality of spaced exhaustinggrooves of said non-contacting seal device are formed.
 6. A substrateprocessing apparatus according to claim 3, wherein said first chamberand said second chamber are communicated through a passage in which aplurality of spaced exhausting grooves of said non-contacting sealdevice are formed.
 7. A substrate processing apparatus according toclaim 4, wherein a member connecting a stage device disposed in saidfirst chamber and drive element disposed in said second chamber extendsthrough said passage.
 8. A substrate processing apparatus according toclaim 5, wherein a member connecting a stage device disposed in saidfirst chamber and drive element disposed in said second chamber extendsthrough said passage.
 9. A substrate processing apparatus according toclaim 6, wherein a member connecting a stage device disposed in saidfirst chamber and drive element disposed in said second chamber extendsthrough said passage.
 10. A substrate processing apparatus comprising: afirst chamber in which a stage device is provided and a substrate loadedon said stage device is processed; and a second chamber providedseparately from said first chamber, a drive element for driving saidstage device being provided in said second chamber, said first chamberbeing maintained in a vacuum and a differential vacuum seal devicecomprising a plurality of vacuum grooves being provided between saidfirst chamber and said second chamber, wherein of said plurality ofvacuum grooves of said differential vacuum seal device, the vacuumgroove which is located closest to said first chamber has an internalpressure lower than or equal to a pressure in said first chamber.
 11. Asubstrate processing apparatus according to claim 10, wherein saiddifferential exhausting seal is disposed in a passage communicating saidfirst chamber with said second chamber, and a member connecting saidstage device and said drive element extends through said passage.